1. Field of the Invention
The present invention relates to a probe head of a three-dimensional coordinate measuring device and to a touch detection method detecting contact with an object.
2. Description of Related Art
Conventionally, coordinate measuring devices, surface texture measuring devices, and the like are known as examples of measuring devices measuring a shape or dimension of a measured object/measureable object/object to be measured. For example, an orthogonal XYZ coordinate system is configured in a measurement space where a measured object is placed. By scanning a touch detection-type probe or the like over the measured object, coordinate values of a surface of the measured object are detected. Based on the detected coordinate values, the shape or the like of the measured object can be measured.
In a three-dimensional coordinate measuring device according to Japanese Patent Laid-open Publication No. 2004-117225, three actuators are respectively provided on each axis so as to displace a contact-type probe along each XYZ axis direction. A ball tip of the probe performs simple oscillation in a plane configured by any two of the three XYZ axes, the oscillation caused by driving two of the actuators corresponding to the two noted axes. The remaining actuator is driven such that the ball tip moves in a circular motion in a plane configured by the remaining axis and an oscillation direction of the simple oscillation. In this state, the ball tip contacts the measured object, and accordingly a contact direction is also detected simultaneously with the contact (Japanese Patent Laid-open Publication No. 2004-117225 specification paragraphs [0014] to [0022], FIG. 1, etc.).
In a three-dimensional coordinate measuring device such as that described above, when sensitivity of the contact detection by the contact-type probe varies dependent on the direction of contact with the contacted object, measurement accuracy of the shape or the like may decrease.